The only thing with which I would disagree a bit is May, 1943 as "ending" the U-boat threat. May is indeed symbolic of the change in fortunes between the allied navies and Kriegsmarine in the 2nd Battle of the Atlantic. But the reality is that the shift in the naval war was more of an evolution. While May 43 can claim the high water point for the U-boats, their losses began to climb in the middle of 42.

I would agree completely when you use the word evolution. Allied nations survived long enough to naturally counter submarine threats, inducing them to try and evolve too. By then it was too late though.

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Originally Posted by Sam-Nary

I've generally considered May of 43 the end of the real threat because the Germans had no real "happy time" after that month. Their losses in that month were so significant that Donitz actually abandoned the Atlantic, but would never again get a shot like what he had at the beginning of the war.

I've seen some sources that would indicate that some of the later German subs might have been able to turn the tide, but they came in far too late to have any real effect on the war.

Im only aware of 2 "happy time" episodes. One in the early years of the war and one when America first entered the war and U-boats were predatory on the coastal regions.

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Originally Posted by redcoat

While you are correct, May 1943 was the month Donitz ordered the withdrawal of his submarine forces from the mid-Atlantic, effectively admitting defeat.
While the U-boats would later return to the mid-Atlantic, they were never to pose a serious threat to the Allied Atlantic convoy routes again.

Im sure that there was a time in 1943 when it the U-boats ascended again, because Americans withdrew most of the support they had offered in the Atlantic, for the Torch landings.

In WWII, given that the German U-boat campaign was far more determined and far better organized, and Germany didn't back off until May 1943 (and mostly due to Allied success at sinking U-boats rather then from a neutral protesting), it's surprising that there wasn't any massive food reduction. Did Britain improve its home methods of farming between the wars? Secure trade deals with Ireland? Or do you think the Germans simply weren't lucky enough to get the ships carrying food... Because I remember in a documentary on the Battle of the Atlantic saying that right before "Black May 1943" that Britain had only a few months supply of fuel oil left... and if that fuel oil was a referance to gasoline/petrolium/diseal fuel a shortage of that would be dangerous.

Britain learned the lesson of WW1 and effectively nationalised all our farm land, mechanised and turned over every available square foot to growing crops including getting people onto allotments to grow their own.
It was a ruthless time, if a farmer didnt meet government production targets regardless of whether he owned the land he was slung off and someone else got it.
Food production was king, legality and morality came second.

There wasnt the availability of mechanisation or modern fertilisers in WW1 that there was in WW2 and we still needed to import food.

Im only aware of 2 "happy time" episodes. One in the early years of the war and one when America first entered the war and U-boats were predatory on the coastal regions.

That sounds about right, though the Germans still managed to do a tremendous amount of damage even in periods that they didn't count as "happy time" periods.

The first one, I think, was set up by the fact that convoys hadn't been formally organized yet, and faded out when they were organized the winter in the North Atlantic made it too rough for the U-boats.

The second one off the US was set up by the fact that America didn't have any blackouts and the ships where lit up by America's major cities.

Britain learned the lesson of WW1 and effectively nationalised all our farm land, mechanised and turned over every available square foot to growing crops including getting people onto allotments to grow their own.
It was a ruthless time, if a farmer didnt meet government production targets regardless of whether he owned the land he was slung off and someone else got it.
Food production was king, legality and morality came second.

There wasnt the availability of mechanisation or modern fertilisers in WW1 that there was in WW2 and we still needed to import food.

If you look at the numbers, less than 2% of allied ships were actually attacked....

The u-boat "campaign" was in fact nothing more than guerilla (or caravan raiding if you prefer) at sea.

Once ships sailed in protected convoys the u-boats effectiveness significantly dropped... Their effect was mostly one of nuisance, forcing ships to sail in slower escorted convoys and forcing the allies to commit air and naval assets to protection of merchant shipping.

There was never any question of the u-boats "winning" the war or even the battle of the Atlantic. Though for dramatic effect both germans and british like to exagerate the effect.

That sounds about right, though the Germans still managed to do a tremendous amount of damage even in periods that they didn't count as "happy time" periods.

Yes true. Im half way through an account of the Atlantic war atm, and its very enlightening. I think though, imo at least, that the "happy times" represented the best chances for the U-boats to cause significant danage though, before the Alles had organised themselves for a counter offensive. The other times they mostly caused problems, were in the "black zones", where convoys could not be escorted properly by convoys, and also where ships got lost out of convoys.

Once the allies fixed set tactics at set points, they were ble to steadily overcome the U-boat tactics, until they could go on the counter offensive with unlimited momentum.

On hindsight, from all the material ive ever read about the Battle of the Atlantic, the U-boats were extremely dangerous, but they could never sink the required tonnage per month that would truly put the ultimate strain on Britains survival, although it did cause immense problems, of course. It was estimated by Donitz that around 700,000 (although it was probably nearer 600,000) tons a month would need to be sunk to put Britain in peril over a year, a target which they could not achieve consistently, even before America put its wn resources into the Batle of Atlantic, which then made it impossible to sink the required tonnage, because the tactics to stop the U-boats were nearing completion. This also confirm the point, that commerce raiding alone, is not enough to win wars, as Mahan rightly stated in his theory.

The Royal Navy may not have been the strongest by this period, but its part was still vital to Britains survival. I also think that the Merchant navy don't get the respect they deserve, in putting their lives on the line time after time. They have my utmost respect. I also respect the fact that the Germans were able to even get inside the U-boats, which were rightly called "Iron coffins", a truly claustrophobic environment.

I have read the account of one commander Herbert A Werner, who was one of the fortunate survivors of the U-boat campaign, and although you can see his sense of optimisn throughout the book, and his own beliefs, he left no illusions on the conditions on serving on a U-boat, and the ultimate problems that arm of the Kriegsmarine faced as the allies continued to put up stoic resistance.

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The first one, I think, was set up by the fact that convoys hadn't been formally organized yet, and faded out when they were organized the winter in the North Atlantic made it too rough for the U-boats.

Agreed.

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The second one off the US was set up by the fact that America didn't have any blackouts and the ships where lit up by America's major cities.

True, but I also believe the Americans were initially reluctant to adopt the convoy system at first, which is partly responsible for the big losses they received.

I'm sure that there was a time in 1943 when it the U-boats ascended again, because Americans withdrew most of the support they had offered in the Atlantic, for the Torch landings.

No.
From May 1943 the effectiveness of the U-boat campaign in the Atlantic declined to such an extent, that in the majority of months after that date more U-boats were sunk, than Merchant ships sunk by U-boat.
For example:
June 1943, 7 Allied merchant ships lost:17 U-Boats lost

July 1943, 29 Allied merchant ships lost: 34 U-Boats lost.

August 1943, 4 Allied merchant ships lost: 20 U-boats lost

The main effectiveness of the continuing U-boat campaign after this date was in forcing the Allies to maintain a convoy system, and the naval resources to defend them.

The second one off the US was set up by the fact that America didn't have any blackouts and the ships where lit up by America's major cities.

It was the lack of a convoy system.

Within a couple of weeks of the convoy system being set up on the US coastal routes Donitz had withdrawn his boats back into the mid Atlantic, the results were no longer were worth travelling the extra distance.

Interesting. I'd never really thought of the U-boat campaign in WWI to be as effective as the Germans backed out of it...

They found that U-boats could easily sink British warships with less risk then German warships would have to take (surface warships that is) and responding to British efforts to blockade Germany decided to unleash their U-boats on British trade in unrestricted submarine warfare, sinking any ship bound for Britain without warning. However, in the early years, this got them in trouble as the US protested these actions after the loss of American lives.

The sinking of the Lusitania, and other British ships carrying American passangers helped turn the tide in the US with regards to supporting the Central Powers or the Allies in the Allies' favor. And since the German Army still looked reasonably strong in 1915, the German government backed off and withdrew its U-boats rather then risk American entry into the war.

The return to unrestricted submarine warfare in 1917 came because the situation for Germany had become desperate and they were looking for rapid ways out. And once the convoy system was introduced, the German effort was broken.

That's why I consider the WWI campaign to be ineffective. The Germans didn't have the will to sustain it early, and once the lone U-boat attacks were thwarted by the convoy system the damage the U-boats did was repared. Tactics born of desperation generally do not work. Even if the U-boats had knocked Britain out in 1917, the return to this warfare likely would have brought the US into the war, and the Germans would trade the British Empire for the United States of America, a nation they couldn't starve into submission. And so long as the French didn't completely collapse, there would still be ports to come into.

In WWII, given that the German U-boat campaign was far more determined and far better organized, and Germany didn't back off until May 1943 (and mostly due to Allied success at sinking U-boats rather then from a neutral protesting), it's surprising that there wasn't any massive food reduction. Did Britain improve its home methods of farming between the wars? Secure trade deals with Ireland? Or do you think the Germans simply weren't lucky enough to get the ships carrying food... Because I remember in a documentary on the Battle of the Atlantic saying that right before "Black May 1943" that Britain had only a few months supply of fuel oil left... and if that fuel oil was a referance to gasoline/petrolium/diseal fuel a shortage of that would be dangerous.

I refer you to David Stevenson's book " 1914-1918 The History of the First World War " pages 321 and 322 of the Penguin Edition 2005. A total of 3.7 million tonnes of British merchant shipping was sunk by the U Boats in the calendar year 1917. The world total of merchant shipping sunk by the U-boats in the same period was 6.2 million tonnes. The no. of British,Allied, neutral ships lost to U Boats rose from 234 in Feb. 1917 to 281 in March, 373 in April, 287 in May,290 in June, 227 in July. So confident was the German Admiralty was, of the effects of the unrestricted warfare of the submarines, that it placed no major orders for new submarines until June 1917, whereas the British counterpart was close to panic.

Few more facts
In WW2 the size of the British Merchant fleet stayed almost level throughout the war at between 16 and 20 million tons, making up the tonnage through purchase, requisition, chartering from neutrals and other means.

Even in the period 1939-41 the size of the British merchant fleet actually increased by three quarters of a million tons.

Amount of Allied merchant tonnage sunk against production of merchant shipping.
1940. Tonnage sunk, 4.01 million : tonnage built 0.78 million